DMX512 is a standard protocol for digital communication networks to control stage lighting and effects, as known for example from http://en.wikipedia.org/wiki/DMX512.
DMX512 was originally designed as a standardized method for controlling light dimmers, which replaced various incompatible proprietary protocols employed previously. However, it soon became the primary method for linking not only controllers and dimmers, but also more advanced fixtures and special effects devices such as fog machines and moving lights.
As to the protocol, at the data-link layer, a DMX512 controller transmits asynchronous serial data at 250 kbaud. The data format is fixed at one start bit, eight data bits, two stop bits and no parity. The start of a packet is signified by a break followed by a logical “mark”, known as the “Mark after Break”. The break, which signals the end of one packet and the start of another, causes receivers to start reception and also serves as a frame (position reference) for data bytes within the packet. Framed data bytes are known as slots. Following the break, up to 513 slots may be sent.
The first slot is reserved for a “Start Code” that specifies the type of data in the packet. A start code of 0x00 (hexadecimal zero) is the standard value used for all DMX512 compatible devices, which includes most lighting fixtures and dimmers.
All slots following the start code contain control settings for slave devices. A slot's position within the packet determines the device and function to be controlled, while its data value specifies the control set point. Multi-byte data values are conveyed in little endian format in adjacent slots.
As the number of lights controlled increases and/or light patterns generated by the lights become more complicate or change more rapidly, massive MCU timing and resources are consumed. The correspondingly heavier data traffic also compromises the signal communication and processing. Amongst other adverse results, the quality of the light pattern deteriorates by, for example, occasional jitters, flickering or unstable lighting.
The invention seeks to mitigate or at least alleviate such a problem by providing a new or otherwise improved control method and controller therefor.